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81.
Dietmar B?nsch Ralph Schneider Ibrahim Akin Cristoph A. Nienaber 《Journal of visualized experiments : JoVE》2012,(60)
Implantable cardioverter-defibrillators (ICDs) terminate ventricular tachycardia (VT) and ventricular fibrillation (VF) with high efficacy and can protect patients from sudden cardiac death (SCD). However, inappropriate shocks may occur if tachycardias are misdiagnosed. Inappropriate shocks are harmful and impair patient quality of life. The risk of inappropriate therapy increases with lower detection rates programmed in the ICD. Single-chamber detection poses greater risks for misdiagnosis when compared with dual-chamber devices that have the benefit of additional atrial information. However, using a dual-chamber device merely for the sake of detection is generally not accepted, since the risks associated with the second electrode may outweigh the benefits of detection. Therefore, BIOTRONIK developed a ventricular lead called the LinoxSMART S DX, which allows for the detection of atrial signals from two electrodes positioned at the atrial part of the ventricular electrode. This device contains two ring electrodes; one that contacts the atrial wall at the junction of the superior vena cava (SVC) and one positioned at the free floating part of the electrode in the atrium. The excellent signal quality can only be achieved by a special filter setting in the ICD (Lumax 540 and 740 VR-T DX, BIOTRONIK). Here, the ease of implantation of the system will be demonstrated. 相似文献
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84.
Erwin Märtlbauer Ewald Usleber Richard Dietrich Elisabeth Schneider 《Mycotoxin Research》2009,25(4):175-186
In a long-term study (1990–1997) on ochratoxin A (OTA) in human blood serum, 102 serum samples from 36 persons of the Munich
Institute for Hygiene and Technology of Food of Animal Origin were analysed by enzyme immunoassay (EIA), and by high performance
liquid chromatography (HPLC) for control. Detection limits were at 50 pg/ml (EIA) and 50–70 pg/ml (HPLC), recoveries were
80–120% (EIA) and 30–60% (LC). OTA was detected in 98% (EIA, 368 ± 217 pg/ml) and 93% (HPLC, 271 ± 170 pg/ml) of samples (maximum
1,290 pg/ml). Using published conversion factors for serum/intake estimates (1.34 or 1.97), the mean daily OTA intake of these
36 persons was 493–725 pg/kg bw. Long-term individual mean OTA levels of nine persons ranged from 162 ± 80 pg/ml to 549 ± 172 pg/ml.
Our data were compared with published OTA serum levels (1985–2008) for apparently healthy persons from a total of 30 countries.
On a worldwide basis, the mean of means for OTA in human serum was estimated to be 700 pg/ml, corresponding to a mean daily
OTA intake of 940–1380 pg/kg bw. This level, which was relatively stable over the last decades, is well below published tolerable
daily intake values (14,000–18,000 pg/kg bw). 相似文献
85.
The effects of alcohols on lipid bilayers: a spin label study 总被引:12,自引:0,他引:12
S J Paterson K W Butler P Huang J Labelle I C Smith H Schneider 《Biochimica et biophysica acta》1972,266(3):597-602
86.
Brown WD Bjork A Schneider K Pitnick S 《Evolution; international journal of organic evolution》2004,58(6):1242-1250
Understanding the evolution of polyandry (mating with multiple males) is a major issue in the study of animal breeding systems. We examined the adaptive significance of polyandry in Drosophila melanogaster, a species with well-documented costs of mating in which males generally cannot force copulations. We found no direct fitness advantages of polyandry. Females that mated with multiple males had no greater mean fitness and no different variance in fitness than females that mated repeatedly with the same male. Subcomponents of reproductive success, including fecundity, egg hatch rate, larval viability, and larval development time, also did not differ between polyandrous and monogamous females. Polyandry had no affect on progeny sex ratios, suggesting that polyandry does not function against costly sex-ratio distorters. We also found no evidence that polyandry functions to favor the paternity of males successful in precopulatory sexual selection. Experimentally controlled opportunities for precopulatory sexual selection had no effect on postcopulatory sperm precedence. Although these results were generally negative, they are supported with substantial statistical power and they help narrow the list of evolutionary explanations for polyandry in an important model species. 相似文献
87.
The alpha and beta subunits of alpha/beta heterodimeric integrins function together to bind ligands in the extracellular region and transduce signals across cellular membranes. A possible function for the transmembrane regions in integrin signaling has been proposed from structural and computational data. We have analyzed the capacity of the integrin alpha(2), alpha(IIb), alpha(4), beta(1), beta(3), and beta(7) transmembrane domains to form homodimers and/or heterodimers. Our data suggest that the integrin transmembrane helices can help to stabilize heterodimeric integrins but that the interactions do not specifically associate particular pairs of alpha and beta subunits; rather, the alpha/beta subunit interaction constrains the extramembranous domains, facilitating signal transduction by a promiscuous transmembrane helix-helix association. 相似文献
88.
J Maimon M Mauro K C Gorray B S Schneider 《The journal of histochemistry and cytochemistry》1991,39(11):1571-1574
Antisera to guinea pig insulin are not commonly available, largely because of the short supply and limited immunogenicity of the intact hormone. To overcome these problems we have employed a novel reagent, synthetic guinea pig insulin B-chain C-terminal decapeptide, as a hapten for raising antibodies that react with intact guinea pig insulin. The decapeptide, coupled to bovine serum albumin, was successfully used as an immunogen in rabbits. The resulting anti-serum was employed for immunocytochemical staining of guinea pig insulin in pancreatic sections. The specificity of the staining was verified by both pre-absorption and pre-immune serum controls. The utility of this new antiserum for investigations of guinea pig insulin physiology is discussed. 相似文献
89.
90.
In primate cells, assembly of a single HIV-1 capsid involves multimerization of thousands of Gag polypeptides, typically at the plasma membrane. Although studies support a model in which HIV-1 assembly proceeds through complexes containing Gag and the cellular adenosine triphosphatase ABCE1 (also termed HP68 or ribonuclease L inhibitor), whether these complexes constitute true assembly intermediates remains controversial. Here we demonstrate by pulse labeling in primate cells that a population of Gag associates with endogenous ABCE1 within minutes of translation. In the next approximately 2 h, Gag-ABCE1 complexes increase in size to approximately that of immature capsids. Dissociation of ABCE1 from Gag correlates closely with Gag processing during virion maturation and occurs much less efficiently when the HIV-1 protease is inactivated. Finally, quantitative double-label immunogold electron microscopy reveals that ABCE1 is recruited to sites of assembling wild-type Gag at the plasma membrane but not to sites of an assembly-defective Gag mutant at the plasma membrane. Together these findings demonstrate that a population of Gag present at plasma membrane sites of assembly associates with ABCE1 throughout capsid formation until the onset of virus maturation, which is then followed by virus release. Moreover, the data suggest a linkage between Gag-ABCE1 dissociation and subsequent events of virion production. 相似文献